DIY FirstWatt Pass B1 w/ Korg Nutube Preamp
Unit works perfectly
Build notes:
- Remote controllable volume and input selection
- Ultra transparent relay-based I/O selector and volume attenuator
- 2 inputs/1 output as built.
- External AMB sigma11 linear regulated PSU with oversized transformer
- Front and rear panels milled at FPE
- Front panel volume level display
- Parmetal Series 20 aluminum chassis -- 12" x 8" x 2"
- 2H distortion set at 9.5V, per Pass default recommendation
- Extensive use of EAR ISODAMP SD125 for damping the Nutube, relay strip and top and bottom chassis panels. This significantly tames the Nutubes microphonic ringing.
- Nichicon Muse UES coupling caps, Panasonic FC caps for CRC. Vishay-Dale RN55 and CPF3 resistors.
- Korg Nutube B1 Preamplifier PCB + Fairchild JFETs – diyAudio Store
- 6moons: audioreviews FirstWatt B1 with Nutube
- Expansion options:
- Blind holes in rear panel allow for expansion for 4 inputs and 2 outputs
- A pot/knob can be added to the center of the front panel to control volume manually in addition to the remote control
Asking $500 shipped, which is about 30% less than what the build costs.
If there isn't much interest, I may wrap this up and use it in the future... it is a great little unit.
P.S life changes require full downsize of my system and projects, all of which I will be selling.
Unit works perfectly
Build notes:
- Remote controllable volume and input selection
- Ultra transparent relay-based I/O selector and volume attenuator
- 2 inputs/1 output as built.
- External AMB sigma11 linear regulated PSU with oversized transformer
- Front and rear panels milled at FPE
- Front panel volume level display
- Parmetal Series 20 aluminum chassis -- 12" x 8" x 2"
- 2H distortion set at 9.5V, per Pass default recommendation
- Extensive use of EAR ISODAMP SD125 for damping the Nutube, relay strip and top and bottom chassis panels. This significantly tames the Nutubes microphonic ringing.
- Nichicon Muse UES coupling caps, Panasonic FC caps for CRC. Vishay-Dale RN55 and CPF3 resistors.
- Korg Nutube B1 Preamplifier PCB + Fairchild JFETs – diyAudio Store
- 6moons: audioreviews FirstWatt B1 with Nutube
- Expansion options:
- Blind holes in rear panel allow for expansion for 4 inputs and 2 outputs
- A pot/knob can be added to the center of the front panel to control volume manually in addition to the remote control
Asking $500 shipped, which is about 30% less than what the build costs.
If there isn't much interest, I may wrap this up and use it in the future... it is a great little unit.
P.S life changes require full downsize of my system and projects, all of which I will be selling.
Attachments
Very impressive build. Kudos. And I love your separate power supply. May I ask what volume/input control system you are using and what remote(s) it will work with?
Thanks for the kind words!
his is a kit I bought from a seller in Russia... I found a Youtube video with a demonstration of it:
YouTube
It came with a slim plastic remote that supports power, volume control and i/o selection. It will come with the unit.
I need to check the manual (it's in Russian so I use Google translate), but it may have remote learning capabilities to use other remotes as well.
I am glad someone purchased that superb looking unit. I have 2 Korg units already, but was tempted it was such a terrific build.
Thanks for the kind words dtaylo3. I am happy that someone took the plunge and will enjoy this great preamp. I may buy a kit to have on standby for the future... in case I get sellers remorse 🙂